Refining mineral lubricating oils



Jan. 26, 1937. w, J c Y 2,069,170

REFINING MINERAL LUBRICATING OI [LS Filed may 9, 1954 ATTORNEY Patented Jan. 26, 1937 v 2,069,170

UNITED STATES PATENT OFFICE 2,069,170 REFINING MINERAL LUBRICATING OILS William J. mom, Alton, ni., assignor to Standard Oil Company, Chicago, 111., a corporation of Indiana Application May 9, 1934, Serial No. 724,674

2 Claims- (CL 196-18) This invention relates to a process of refining exchanger 20 and into deasphalting drum 2| mineral lubricating oils and particularly to where a separation into two layers is allowed to mineral lubricating oils containing paraflin wax. take place. Heat exchanger 20 may be supplied One of the objects of the invention is to proby cooling water or steam as an additional means vide a method for removing paraffin and petroof controlling t t p tu e The pp layer I 5 latum waxes from such oils. Another object of consists of a solution of oil in p p and the the invention is to remove asphaltic constituents low r lay r c n is s f a ol i n of pr pa in from oils of the residual type, a combination d the asphaltic constituents of the oil. The presasphalting and dewaxing process. Still another sure in this drum will usually be about 200 object of the invention is to provide greater pounds p Square c gage at a d ab ut economy in the deasphalting of residual oils 600 pounds P Square inch at y e than has heretofore been achi ved, ulating the temperature the amount of material The invention will be more clearly understood cted from the oil by the liqui P p can from the accompanying drawing which forms be regulated to any desired degree is p a part of this specification and diagrammaticale ferred to Op at a mp tu o ab ut 150 15 ly illustrates an elevational plan of my apparat0 With a ut of about at t V which temperature approximately -35% of the The drawing will be described in con ti residuum is extracted, but at greater dilutions with the operation of the process in the refining 011 With Propane, this p tur Will be of a typical residual o in this case a rel w r and vice versa- 20 sidue obtained from the distillation of midcon- The pp layer in S p ato 2| ebn ist O 20 tinent crude oil. This residual oil is introduced the P p extract is Withdrawn y l 22 a by line In into absorber II where it is brought Passed through heat exchanger 3 i t ch g into contact with hot propane vapors supplied chambers 24 and The t x h e 23 by line I2, as will be hereinafter d d, The may be employed to reduce the temperature to 25 hot propane vapors pass upwardly through the s m int rm at point. f r x p absorber which may be provided with itab but it is preferred not to lower the temperature contact means, such as baiile plates, bubble cap y. t means to a Point Where y appreciable plates, etc. The 'hot propane va ors comin amount of waxy constituents in the oil are caused in contact with the residual oil condense and disto separater t p rp e, old filtrate from an solve therein, serving to heat the oil to the defilter 3| Subsequently described, y be forced sired temperature. The temperature of the eny Pu p 34 through yp s lines 3 11 and 34b tering propane vapors may be between 150 and to and from heat exchanger 23. Chambers 24 300 F. and the resulting mixture of propane and and 25 are Suitably heat su a ed s is a so residuum is withdrawn from the base of the abdrum 2| where it is essential to pr ingress 3i sorber by line l3 at a temperature between ss heat from the Surrounding tm and 200 F. phere during the operation of the process.

Valved line I4 is provided for withdrawing any Chilling chambers 24 and 25 are employed aluncondensible vapors. In the upper part of the ternetely the following manner; P p 4Q absorber I may employ a cooling coil l5 suitably solution is charged into one chamber until it is 4' connected to a source of cooling water by line filled approximately to two-thirds of its capacity. I8, discharging by line H. By regulating the The inlet valve is then closed and the valve in amount of cooling provided by cooling coils l5 one of the vapor l e 25 p d' y the temperature of the outgoing mixture of reto l ow pr p n v p r to pa n mp r siduum and propane is partly controlled. The 1 by wh ch they are orced into line previous 4 temperature of this mixture is also controlled to ly described. By this means the pressure is an extent by introducing liquid propane into the gradually diminished in the chilling chamber absorber by line l8. Liquid propane added in and as a result part of the liquid propane is this way'also serves to regulate the composition evaporated from the propane-oil solution, bring- 50 oi the mixture withdrawn from the absorber ing about the lowering of the temperature to any 5 which should usually lie between one and onepoint desired. In order. to obtain complete rehalf to five volumes of propane per volume of moval of the waxy constituents from the oil it residuum. is desirable to reduce the temperature by this The hot mixture of propane and. residuum from means to approximately -40". F. It is impor- 55 the absorber is forced by pump l9 through heat tant to regulate the rate oi. cooling, preferably not to exceed approximately -3 per minute in order to promote larger crystal growth in the separating wax, resulting in higher filtration rates in the subsequent step to be described.

While one chilling chamber is being cooled in the above manner the stream from line 22 is diverted to the other chilling chamber. If desired additional liquid propane may be introduced into the stream from propane storage by pump 28 and line 28a, providing an independent means of controlling the amount of propane in the cold slurry obtained in the chilling chamber is provided. Ordinarily this slurry should contain between 60 and 70% of propane.

The cold slurry from the chilling chambers is withdrawn by line 29 and forced by pump 30 into filter press 3| where the separated wax is removed. This press may be of the continuous type, employing a revolving filter element dipping in a bath of the slurry with means for removing the wax from the filter element, washing the wax cake with additional propane, etc. If de sired, a battery of batch filter presses may be employed in place of the continuous filter.

The wax is discharged by line 32 and the waxfree filtrate by line 33 and pump 34 by which it is introduced under pressure to propane recovery tower 35, equipped with a heating coil 36, by which the temperature is raised to a 30 point where substantially all the propane is evap- 35 pressure.

orated from the filtrate under pressure. The vapors are discharged by line 31 and thence to condenser 38 where they are reliquefied and collected in storage tank 39, suitably maintained under If desired, part of the propane vapors may be diverted by valve 40 and line 4| to line l2, previously described. The filtrate which is now substantially free from propane is discharged by line 42 to a suitable storage tank for 4.9 refined lubricating stock. It may suitably be filtered through fullers earth to further improve the color. It may also be, further refined by treatment with sulfuric acid, extraction with selective solvents such as cresylic acid, beta-betadichlor-diethyl ether, etc.

Returning now to that portion of the oil remaining undissolved in the propane in separator 2|, this is withdrawn by line 43 and forced by pump 44 into propane recovery tower 45. Heat supplied by coil 46 drives oil the propane which passes by vapor line 41 and line 31 to condenser 38. as previously described. The oil remaining after removal of propane is withdrawn by line 48 leading to storage tank not shown. This oil is high in asphaltic constituents and is suitable mainly for the production of asphaltic road oils and fuel oil, or it may be used as a charging stock for certain types of cracking processes. When subjected to coking it produces a gasoline-containing distillate useful for the manufacture of high octane value motor fuels.

Instead of using a residual oil as the charging stock for my process I may use mineral lubricating oil distillates, particularly those distillates of high viscosity of the order of '75 to 1'75 seconds Saybolt at 210 F. When using distillates of this type the oil obtained from tower 45 will contain very little asphaltenes and is suitable for certain uses as a high viscosity lubricating oil but will ordinarily have a lower viscosity index than the more highly refined oil obtained from the upper layer in drum 2| is of lower viscosity and suitable for the production of the lighter grades oi lubricating oil when higher viscosity index and resistance to sludging is required. This lightei oil may be blended with the heavier oil iron the lower layer to produce intermediate lubricating oil grades.

By suitably regulating the temperature anc propane concentration in separator drum 2| it i: possible to retain both the paraffin wax and pet rolatum wax in solution in the propane formin; the upper layer or, if desired, the temperatun may be raised to a point between 180 and 200 F. at which point the parafiln wax will be extractel with the propane and the petrolatum wax wii remain in the insoluble lower layer with th heavier oil. Under this condition it will b necessary to further dewax the oil in the lowe layer and this may be done by reducing the tem perature of this material to about F. an treating with further quantities of liquid propan which will extract the petrolatum and rejec most of the asphalt. Operating in this manne: I may eliminate as much of the difiicultly filtei able heavy waxes from the propane-oil solutio as desired, greatly facilitating the filtration parafifin accompanying the oil in the proper layer withdrawn by line 22.

In the foregoing description of my invention have illustrated the process as applied to the It fining of a 40% midcontinent residue. It shoul be understood, of course, that I may reduce tl crude oil initially to a lower percent residue the 40%. For example, I may conveniently use 25 residue, especially when making the more visco1 lubricating oils. The process is also applicab to other types of crude oil such as Pennsylvani Texas, Salt Creek or California crudes, althoug the proportions of propane, temperature of a phalt separation, etc. will vary somewhat wi different crudes, depending on the asphalt co: tent of the residue.

Prior to charging the residue to my process may give it a preliminary treatment with sulfur acid or I may subject it to extraction with selective solvent to remove oils of low viscosi index naphth'enic characteristics. In this ca: when using residues refined in this manner I pr fer to operate the process to produce two grad of lubricating oil, as previously described, wh working with distillate products. My inventi provides a particularly advantageous method separating asphalt and/0r heavy constituer from lubricating oils by absorbing hot propa vapors therein and subsequently refrigerati and dewaxing the oil, recompressing and cycli propane vapors from the dewaxing stage to t initial separating stage. Heat and power 2 both conserved by this operation and the oil refined with a minimum of handling and loss propane. Throughout this specification I me tion the use of propane as the diluent and solvent. However, it should be understood tl I do not intend to limit the process to the use pure propane as I prefer to use a commerc grade of propane which contains some ethz and normal and iso-butane, which constitue alter the properties of propane to some extl but do not interfere with the successful carry out of the process. Although I have descrll my process with respect to specific examples is intended to be limited only by the follow claims:

I claim:

1. The process of refining a viscous hyd carbon lubricating distillate containing parafiin and petrolatum wax, which comprises absorbing hot propane vapors therein until the oil is separated into two phases; regulating the temperai-ure between 160- and 200 F., whereby the oil is separated into a lighter phase containing easily filterable paraflin wax and a heavier phase containing a difiiculty filterable petroleum wax; cooling and refrigerating said lighter phase; then filtering crystallized wax from the refrigerated material and subsequently recovering the v propane vapors propane contained therein; recovering the propane from said heavier phase; recompressing and absorbing said vapors while still hot with the heat of compression in said original lubricating oil distillate.

2. The process of claim 1 wherein the propane" is recovered from said oil phases by distillation under pressure and hot propane vapors produced thereby are absorbed directly in the lubricating oil stock charged to the process.

WILLIAM J. McGllL. 

